The invention relates to an electrical connecting device for transmitting electrical energy and/or data between a first electrical component, which is arranged in a first housing which is electrically connected to a reference potential, and a second electrical component, which is arranged in a second housing which is electrically connected to the reference potential. The invention also relates to an on-board electrical system comprising an electrical connecting device, and to a motor vehicle comprising an on-board electrical system.
Electrical connecting devices can be embodied as cables and serve to transmit energy and/or data between electrical components. Electrical components of this kind can be components of an on-board electrical system of a motor vehicle, for example electrical energy stores for providing electrical energy, control units, communication devices, display elements or electric motors.
An electrical connecting device or cable usually comprises an electrical conductor, for example a wire or braids. For reasons of electromagnetic compatibility (EMC), the electrical conductors generally have a shield. Therefore, undesired electrical or electromagnetic effects, for example coupling in or emitting electrical or electromagnetic fields, can be avoided. To this end, the shield is connected to a reference potential, for example the reference potential of the motor vehicle, at both ends of the cable.
This has the disadvantage that so-called ground loops can be produced by uncontrolled currents flowing across the shields of the conductors, said uncontrolled currents, for their part, possibly causing interference in respect of electromagnetic compatibility. When there is a defect in the connection to the vehicle ground or when there is a faulty ground connection, currents which are so high that the motor vehicle may be damaged can flow in the process. This is problematical primarily when transmitting high-voltage energy via the lines since electrical high-voltage components generally have a high current consumption and/or can provide a high current.
An object of the invention is to realize an electrical connecting device by means of which ground loops and uncontrolled flow of currents can be safely and reliably avoided.
According to the invention, this object is achieved by an electrical connecting device, an on-board electrical system and also a motor vehicle having the features as claimed in the respective independent patent claims. Advantageous embodiments of the invention are the subject matter of the dependent patent claims, the description and the figures.
An electrical connecting device according to the invention comprising an electrical conductor serves to transmit electrical energy and/or data between a first electrical component, which is arranged in a first housing, and a second electrical component, which is arranged in a second housing, wherein the first housing is electrically connected to a reference potential, and the second housing is electrically connected to the reference potential. According to the invention, the electrical connecting device has a first shielding device for shielding the electrical conductor, wherein the first shielding device can be electrically connected to the first housing, and a second shielding device for shielding the electrical conductor, wherein the second shielding device can be electrically connected to the second housing, and wherein the first shielding device is electrically isolated from the second shielding device.
In other words, this means that the first electrical component can be electrically connected to the second component by means of the electrical conductor of the electrical connecting device, so that data and/or energy can flow between the electrical components. The electrical connecting device can be embodied as at least one cable which comprises the electrical conductor, for example in the form of a wire or in the form of braids. The first electrical component and the second electrical components are each arranged in a housing, wherein each of the two housings is connected to a reference potential.
In order to protect the electrical connecting device against interfering influences, the electrical connecting device has a first shielding device and a second shielding device. In this case, the first shielding device can be connected to the first housing and therefore also to the reference potential of the motor vehicle. The second shielding device can be connected to the second housing and therefore likewise to the reference potential of the motor vehicle. The first shielding device and the second shielding device can, for example, be woven one into the other and in the process electrically isolated from one another. Since the first shielding device and the second shielding device are electrically isolated from one another, no undesired current can flow across the first shielding device and the second shielding device between the first housing and the second housing. Therefore, the cable is shielded in a bidirectional manner by means of the two shielding devices. In particular, a so-called ground loop, that is to say an electrical circuit which comprises the reference potential, the first and the second housing, and the first and the second shielding device, can be avoided. Damage to the electrical components or danger to persons is advantageously prevented by virtue of this electrical isolation.
In a preferred refinement, the first shielding device and/or the second shielding device are of substantially hollow-cylindrical design, wherein the first shielding device has a first diameter and the second shielding device has a second diameter which is larger than the first diameter. A hollow-cylindrical shielding device of this kind can be a sheath which can surround the electrical conductor of the electrical connecting device, which electrical conductor is embodied as a wire or braid for example. In this case, the first, hollow-cylindrical shielding device can be electrically connected to the first housing and extend over a first conductor subregion in the direction of the second housing at one of the ends of the first shielding device. The first conductor subregion of the electrical connecting device therefore has a concentric design which comprises the at least one electrical conductor and the first, hollow-cylindrical shielding device. In this case, the second, hollow-cylindrical shielding device can be electrically connected to the second housing and extend over a second conductor subregion in the direction of the first housing at one of the ends of the second shielding device. The second conductor subregion of the electrical connecting device therefore likewise has a concentric design which comprises the at least one electrical conductor and the second, hollow-cylindrical shielding device. A hollow-cylindrical shielding device of this kind can be formed in a particularly simple manner.
It has proven advantageous when the first shielding device and/or the second shielding device are formed from an electrically conductive material, in particular a metal. Therefore, electrical and/or electromagnetic fields can be shielded in a particularly effective and efficient manner, so that electrical energy and/or data can be transmitted with a low level of interference.
The second shielding device preferably surrounds the first shielding device at least in regions in a predetermined overlap region. In this case, the overlap region can be located between the first conductor subregion and the second conductor subregion. Since the second shielding device preferably has a larger diameter than the first shielding device, the overlap region of the electrical connecting device has a concentric design which comprises the electrical conductor, the first shielding device and the second shielding device. In the predetermined overlap region, the hollow-cylindrical shielding devices therefore run one over the other. In particular, the electrical connecting device is doubly shielded in the predetermined overlap region. Since the first shielding device is electrically connected to the first housing and the second shielding device is electrically connected to the second housing, the electrical connecting device is shielded in a bidirectional manner in particular.
Provision can be made for an electrical insulation element for electrically isolating the first and the second shielding device to be arranged between the first and the second shielding device in the overlap region. An insulation element of this kind can be an insulating casing which is likewise of hollow-cylindrical design. Provision can also be made for the first shielding device to be integrated into a cable sheath which is composed of an insulating material and has a first diameter. The second shielding device can likewise be integrated into a cable sheath which is composed of the insulating material and has a second diameter which is larger than the first diameter. The cable sheaths can be guided one over the other in a particularly simple manner in the overlap region. In this case, the insulating material of the cable sheaths forms the electrical insulation element which electrically isolates the first shielding device from the second shielding device which runs, in particular, over the first shielding device.
The invention also includes an on-board electrical system for a motor vehicle comprising at least one electrical connecting device according to the invention. In addition, the on-board electrical system comprises a first electrical component, which is arranged in a first housing, and a second electrical component, which is arranged in a second housing, wherein the first electrical component is electrically connected to the second component by means of the at least one electrical connecting device, and wherein the first housing is electrically connected to a reference potential and the second housing is electrically connected to the reference potential. In this case, the first shielding device of the at least one electrical connecting device according to the invention is electrically connected to the first housing, and the second shielding device is electrically connected to the second housing. Ground loops and uncontrolled flow of currents across the shielding devices can be avoided by electrically isolating the first shielding device from the second shielding device.
The on-board electrical system particularly preferably comprises at least one third electrical component which is electrically connected to the first and/or the second electrical component. The on-board electrical system can therefore be extended by any desired number of electrical components and is very safe and reliable owing to the electrical isolation of the first shielding device from the second shielding device.
In an advantageous embodiment, the first electrical component is embodied as a high-voltage battery and/or the second electrical component is embodied as a voltage converter and/or the third electrical component is embodied as a low-voltage battery, wherein a negative pole of the low-voltage battery is electrically connected to the reference potential of the motor vehicle and a positive pole of the low-voltage battery is electrically connected to the voltage converter. The high-voltage battery, which provides a high voltage, is connected to the voltage converter, for example a DC/DC converter, by means of the at least one electrical conductor. Here, a high voltage is intended to be understood to be an electrical voltage of greater than 60 volts. The voltage converter can be designed to convert the high voltage into a low voltage for charging the low-voltage battery. Here, a low voltage is intended to be understood to be an electrical voltage of less than 60 volts. To this end, the voltage converter is electrically connected to a positive pole of the low-voltage battery. The negative pole of the low-voltage battery is connected to the reference potential of the motor vehicle. This means that the vehicle ground is the negative potential of the low-voltage battery. The low-voltage battery is electrically connected to the first housing, in which the high-voltage battery is arranged, by means of the ground connection, and is electrically connected to the second housing, in which the voltage converter is arranged. Owing to the electrical isolation of the first shielding device and the second shielding device, it is advantageously possible to prevent an electric current, which is provided by the low-voltage battery, from flowing between the first and the second housing, for example in the case of a defective ground connection.
As an alternative, the first component and/or the second component are communication devices, wherein the electrical connecting device is designed to transmit data between the first component and the second component. The transmission of data can be ensured with a particularly low level of interference and in a reliable manner by avoiding ground loops by means of the electrical isolation of the shielding device.
The invention also includes a motor vehicle comprising an on-board electrical system according to the invention. The motor vehicle is embodied, in particular, as a passenger car.
The preferred embodiments presented with reference to the electrical connecting device according to the invention apply in a corresponding manner to the on-board electrical system according to the invention and to the motor vehicle according to the invention.
Further features of the invention can be gathered from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description and the features and combinations of features mentioned below in the description of the figures and/or shown in the figures alone can be used not only in the respectively indicated combination but also in other combinations or on their own.
The invention will now be explained in greater detail on the basis of a preferred exemplary embodiment and with reference to the drawings, in which:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.